... So if you check your texts often while trying to work, you aren’t only losing the little bursts of time you spend looking at the texts — you are also losing the time it takes to refocus afterwards, which can be much longer. This means that if your Screen Time shows you are using your phone four hours a day, you are losing much more time than that in lost focus.
A small study commissioned by Hewlett-Packard looked at the IQ of some of their workers in two situations. At first they tested their IQ when they were not being distracted or interrupted. Then they tested their IQ when they were receiving emails and phone calls. The study found that ’technological distraction’ — just getting emails and calls — caused a drop in the workers’ IQ by an average of ten points. To give you a sense of how big that is; in the short term, that’s twice the knock to your IQ that you get when you smoke cannabis. So this suggests in terms of being able to get your work done, you’d be better off getting stoned at your desk than checking your texts and Facebook messages a lot.*
*James Williams, Stand Out Of Our Light (Cambridge: Cambridge University Press, 2018), p. 69.
(Stolen Focus: Why You Can’t Pay Attention by Johann Hari)